title: A dynamic nuclear polarization strategy for multi-dimensional Earth's field NMR spectroscopy.
abstract: Dynamic nuclear polarization (DNP) is introduced as a powerful tool for polarization enhancement in multi-dimensional Earth's field NMR spectroscopy. Maximum polarization enhancements, relative to thermal equilibrium in the Earth's magnetic field, are calculated theoretically and compared to the more traditional prepolarization approach for NMR sensitivity enhancement at ultra-low fields. Signal enhancement factors on the order of 3000 are demonstrated experimentally using DNP with a nitroxide free radical, TEMPO, which contains an unpaired electron which is strongly coupled to a neighboring (14)N nucleus via the hyperfine interaction. A high-quality 2D (19)F-(1)H COSY spectrum acquired in the Earth's magnetic field with DNP enhancement is presented and compared to simulation.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Post Office Box 600, Wellington 6012, New Zealand.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Halse
authors.forename: Paul T
authors.initials: PT
authors.lastname: Callaghan
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D018534:Earth, Planet; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics / Q000379:methods*; D008962:Models, Theoretical; D011874:Radiometry / Q000379:methods*